Drivers Overview

A Driver translates { sql, params, columnTypes } into rows. Drivers are thin: no query logic, just transport. Adding a database means writing a Driver

• a Dialect — no query/IR code is duplicated.

The Driver interface

Every driver implements the same interface:

• query(sql, params) — run a statement, return rows
• transaction(fn) — run a function in a transaction
• borrow() (Postgres) — per-call scoped client from a pool

Registration

Drivers self-register on import via registerDriver. You just import the package and name the driver in config:

import "@mountsqli/driver-sqlite"; // registers "sqlite"

const db = mountsqli({ driver: "sqlite", url: ":memory:", tables: [users] });

Available drivers

Package	Name(s)	Notes
@mountsqli/driver-sqlite	sqlite	zero-dep node:sqlite, Node ≥ 22.5
@mountsqli/driver-postgres	postgres, pg	pg, $N params
@mountsqli/driver-mysql	mysql	mysql2, ? params

Why config-only multi-driver?

Switching databases is a configuration detail. The same QueryPlan runs on any driver — the dialect decides ? vs $N. No query logic is duplicated per driver.

Best practices

• Import the driver package once at startup so it registers.
• Pick the driver by deployment, not by code (keep plans portable).

Common mistakes

• Forgetting to import the driver package — unknown driver error.
• Assuming SQL is identical across dialects (use the plan; the dialect handles it).

Related

• SQLite — zero-dep option.
• Postgres — pooled, $N params.
• Compiler & Dialects — ? vs $N.